MG Siegler in Going Against The Grain:

We’re seeing over and over again now that the behemoths can’t simply add a startup’s funtionality into their own app as a feature and kill said startup. But it’s equally important to note that if you are able to establish your startup, especially those in apps form, it may be hard to get your users to do anything other than what they originally came to do. Especially if the new funtionality is against the grain in any way.

This comes back to understanding what job users hire your product to do for them, and realizing that it’s very difficult to convince them to use the product for a different job.